Many photoresist strippers and residue removers have been proposed for use in the microelectronics field as downstream or back end of the manufacturing line cleaners. In the manufacturing process a thin film of photoresist is deposited on a substrate material, and then circuit design is imaged on the thin film. Following baking, the exposed resist is removed with a photoresist developer. The resulting image is then transferred to the underlying material, which is generally a dielectric or metal, by way of plasma etch gases or chemical etchant solutions. The etchant gases or chemical etchant solutions selectively attack the photoresist-unprotected area of the substrate. As a result of the plasma etching process, photoresist and etched material by-products are deposited as residues around or on the sidewall of the etched openings (vias) on the substrate and the photoresist.
Additionally, following the termination of the etching step, the resist mask must be removed from the protected area of the substrate so that the next process operation can take place. This can be accomplished in a plasma ashing step by the use of suitable plasma ashing gases or wet chemical strippers. Finding a suitable cleaning composition for removal of this resist mask material without adversely affecting, e.g., corroding, etching or dulling, the metal circuitry has also proven problematic.
As microelectronic fabrication integration levels have increased and patterned microelectronic device dimensions have decreased, it has become increasingly difficult to provide suitable photoresist stripping and cleaning compositions that provide suitable stripping and cleaning properties without producing other detrimental effects. In the area of semiconductors and flat panel displays (FPD), the problem of metal corrosion during photoresist stripping, residue removal and the water rinse is a severe drawback, particularly with the use of select metals such as aluminum, titanium, and tungsten and alloys.
A typical residue remover for microelectronic applications might be an alkaline-containing composition that includes polar organic solvents blended with organic amines or hydroxylamines or other strong bases typically in polar organic solvents and other solvating agents in an attempt to lessen metal and dielectric attack or corrosion. Amines, hydroxylamines and other strong bases have been shown to increase the effectiveness of photoresist and residue removal in solvent blends. However, such alkaline ash residue removal formulations experience carbon dioxide uptake from the air, which in most cases shortens the cleaner solution's effective bath life. Moreover, these alkaline cleaner compositions are relatively slow acting and require the substrates to be kept in the cleaner solutions for extended times at elevated temperatures. Moreover, the water rinse following this type of remover can create a strongly alkaline aqueous solution and that can lead to considerable loss of metal from the patterned lines, particularly aluminum which is very sensitive to corrosion in alkaline aqueous solution. This necessitates an intermediate rinse between the cleaning/stripping step and the aqueous rinse. Such an intermediate rinse, typically with isopropyl alcohol, adds undesirable time, safety concerns, environmental consequences, and cost to the manufacturing process.
There is, therefore, a need for stripping and cleaning compositions for photoresists and residues that enable one to completely remove etch and/or ash residue, as well as bulk photoresist, from the microelectronic substrate, especially a need for such cleaner and residue removing compositions that do not produce any significant metal corrosion.